4,5,6,7-tetrahydrobenzotriazoles and process of making the same

ABSTRACT

1. A 4,5,6,7-TETRAHYDROBENZOTRIAZOLE OF THE GROUP CONSISTING OF COMPOUNDS HAVING THE FOLLOWING FORMULAE:   1-R1,R2-4,5,6,7-TETRAHYDRO-1H-BENZOTRIAZOLE AND   2-R1,R2-4,5,6,7-TETRAHYDRO-2H-BENZOTRIAZOLE   IN WHICH R1 IS HYDROGEN OR AN ALKYL RAICAL CONTAINING UP TO 18 CARBON ATOMS, AND R2 IS A CARBOXYL OR LOWER ALKOXYCARBONYL RADICAL, AND ACID ADDITION AND QUATERNARY AMMONIUM SALTS THEREOF.

United States Patent C "i e 9849433 Patented Nov. 19, 1974 It is therefore an object of the invention to provide for 3,849,433 a process whereby benzotriazole and substituted benzo- 495:697'TETRAHYDROBENZOTRIAZOLES AND triazoles can be hydrogenated smoothly and at a desirable PROCESS OF MAKING THE SAME speed and with good yields.

Ivan Butula, Zagreb, Yugoslavia, assignor t Rheint 1 Chemie Rheinau GmJLH', Mannheim, Germany Ano her ob ect of the invention 18 to en arge the group of obtainable substituted tetrahydrobenzotriazoles and t0 gg fia ga 2:35:53:gigg g fif zf i provide novel, heretofore unknown substituents of 4,5,6,7-

p 19 43 794,6 tetrahydrobenzotriazoles.

I t, @L (307d 55/04 A still further object of the invention is to provide acid US. Cl. 260-308 B 13 Claims addition salts and quaternary ammonium salts of the tetrahydrobenzotriazoles.

A more specific object of the invention is to form new ABSTRACT OF THE DISCLOSURE substituted tetrahydrobenzotriazoles which are useful as 4,5,6,7-tetrahydrebenzetriazeles of h f r corrosion inhibitors, acid passivating agents, metal re- 15 strainers, anti-aging agents for use in mineral oils, lubri- R cating oils, heating oils and rubber. Further objects are N N substituted benzotriazoles which are useful as intermediates for making various pharmaceuticals, dyes such as H N or N=Rl 0 erization catalysts for isocyanate addition reactions, and

/ azo-dyes, agricultural chemicals, dyeing additives, polym- N as curing agents for epoxy resins. In so far as the quaterl nary ammonium salt of the tetrahydrobenzotriazoles are concerned, the object is to form ammonium salts which wherein R R and R are hydrogen or organic radicals may be useful as surface"actlve agents' defined in the specification, with the proviso that if R SUMMARY OF THE INVENTION and R are hydrogen, then R must be other than hydro- The compounds of the invention are 4,5,6,7-tetrahydrobenzotriazoles of the formulae The compounds, including those where R R and R are all hydrogen and those where R is phenyl, are made by hydrogenating the compound in the form of their acid [131 [1b] addition salts by adding a solvent in which the acid addi- R2 N R2 N tion salt is at least partially soluble or, if the starting prodnet is in the form of a free base, by adding at least one or N Rl equivalent of acid for each basic group. The reaction in both cases is carried out in the presence of a palladium, N R3 N rhodium or platinum catalyst. The obtained salt may then L be converted to the free base by addition of alkali or the 1 free base may be converted to the acid addition salt or wherein quaternary ammonium salt by addition of an acid, preferably a strong acid, or ammoniating agent. R is hydrogen, straight or branched alkyl of 1-18 car- The compounds of the invention are principally useful bOTl atoms, cycloalkyli alkylcycloalkyl 0r y y as corrosion inhibitors. They also are antioxidants and alkyl of CaFPOH atoms in the alkyl group and intermediates for making various pharmaceutical and mambers in the) Tmg, a 116x055, Pentose or tetrose Sugar agricultural h i al residues or wherein R is A-Z, A being a straight or branched alkyl of 1-4 carbon atoms and Z being amino, lower monoal'kylamino, lower dialkylamino,

BACKGROUND OF THE INVENTION morpholino, N-pyrrolidine, N-piperidino, N-pipera- Few 4,5,6,7-tetrahydrobenzotriazoles have become Zino, y -p p Y Y- known heretofore, and little use has been made of the lower Y "l{ P Y Y Y- Q compounds. These tetrahydrobenzotriazole derivatives yn-N-pip y y y l' y y have been made by total synthesis; see K. Adler and alkylamino-ethylamlnocarbonylalkyl, dlfllkylalfllnofilh- W. Steni, Liebigs Annalen der Chemie, 501, p. 47 1933 oxyearbenylelkyh the last four groups having G. Wittig and w. Krebs, Chem. Ber. 94, p. 3274 (1961); Carbon atoms In alkyl, earbexyeyelehexyl. p y R. Fusco et al., Gazz. Chim. Ital. 91, pp. 849 and 933 alkylphenyl, yp e v the last two r p havlng (1961) since most benzotriazole derivatives are highly re- 1 0r 2 carbon atoms H1 alkyl and Y, respectlvely, sistant against reducing agents. For instance, l-hydroxyfluorlne, trlfiueremethyl, carboxyphenyl, P y y methyl-benzotriazole could not be hydrogenated with of carbon atoms Y i fiuorophenylalkyl, LiAlH, or Raney-Nickel or a Pd-carbon catalyst; see yp y e y v p y l y e a three Gaylord, I. Am. Chem. Soc. 76, p. 285 1954 Likewise, groups hevmg a Carbon atoms In aeyl, lmldazelyll-phenyl-benzotriazole could not be hydrogenated with alkyl, ttlazolylalkyl or tetrawlylalkyli the azoly] either LiAlH, or with Raney-Nickel as catalyst. In using groflpss havmg carbcfn atoms alkyl; zinc amalgam as reducing agent, the reaction resulted in R2 bemg hydrogen Stralght or branched alkyl of 148 an opening up of the triazole ring in the benzotriazole and carbon atoms cyclohexyl, P 1 carboxyl, or alkOXY formation of Z-amino-diphenylamine; see Masao Wakae m of 1-4 carbon the alkoxy group and et al., Osaka Turitsu Kogyo Shoreikan Hokoku No. 27, Wherem pp. 46-47 (1962)C.A. 61, 3096b (1964). R lsbhydrtogen or branched or stralght alkyl of 1-4 Similar reductive opening up of the triazole ring of bencar a Oms, zotriazole upon formation of phenyldiamine derivatives Wlth the Provlslo that If both R2 and R3 are hydro has been described in other publications; see Stetter, then R1 must be than hydrogen Chem. Ber. 86, p. 69 (1953) and Burton et al., J. Chem. 70 and the acid addition salts and quaternary ammonium Soc. (London), Sect. C, 1968, pp. 1268-1273. salts of the said tetrahydrobenzotriazoles.

The compounds of the invention and including those where all of R R and R are hydrogen and those wherein R is phenyl are made by hydrogenating the compound in the form of their acid addition salts by adding a solvent in which the acid addition salt is at least partially soluble or, if the starting product is in the form of a free base, by adding at least one equivalent of acid for each basic group. The reaction in both cases is carried out in the presence of a palladium, rhodium or platinum catalyst. The obtained salt may then be converted to the free base by addition of alkali or the free base may be converted to the acid addition salt of quaternary ammonium salt by addition of an acid, preferably a strong acid, or ammoniating agent.

The invention also embraces the use of the tetrahydrobenzotriazoles and derivatives thereof as corrosion inhibitors and the process of making 4,5,6,7 tetrahyde benzotriazoles by hydrogenation of benzotriazoles.

DETAILED DESCRIPTION OF THE INVENTION AND OF THE PREFERRED EMBODIMENTS The terms in this specification and in the claims such as lower alkyl, lower alkylene, lower alkylamino-, dialkylamino or alkylenediamino are intended to include groups having from 1 to 8 carbon atoms.

The salts of 4,5,6,7-tetrahydrobenzotriazoles referred to herein may be salts of inorganic or organic acids and include also the quaternary ammonium salt. Examples for suitable inorganic acids for forming these salts are the hydrogen halide acids, sulfuric acid, phosphoric acid, nitric acid and perchloric acid. Examples of suitable organic acids are acetic acid, propionic acid, oxalic acid, maleic acid, succinic acid, alkyland alkenyl-succinic acids, aliphatic, cycloalphatic and aromatic sulfone acids, such as petroleum sulfonic acids, mahogany sulfonic acids, p-toluenesulfonic acids and p-dodecylbenzenesulfonic acid and picric acid.

The quaternary ammonium salts of the invention are derived from the usual alkylation agents such as alkyl-, cycloalkylor arylalkyl halides, for instance methyl bromide and ethyl iodide or dialkylsulfates.

The novel compounds of the invention and also the few heretofore known compounds such as the unsubstituted 4,5,6,7-tetrahydrobenzotriazoles and the known substituted 4,5,6,7 tetrahydrobenzotriazoles such as l-phenyland 1-phenyl-5-rnethyl-4,5,6,7-tetrahydr0benzotriazole, are made by hydrogenating a benzotriazole of the formulae [IIa] R2 N R2 N Q N or E1 N-Rl R3 N R N wherein R R and R have the meaning as above given and all of the three groups may also be hydrogen, and R may also be phenyl, in the presence of a palladium, platinum or rhodium catalyst. The reaction is carired out using an acid addition salt of the above-given benzotriazoles as starting product or, if the reaction starts from the free base, it is carried out in the presence of at least one equivalent of acid for each basic group.

The process of the invention is generally characterized by the following stages:

If the groups identified as R R and R are themselves hydrogenizable groups, or have attached thereto such groups, they may be subject also to hydrogenation under specific conditions.

The novel process basically involves a hydrogenation of the benzene nucleus of benzotriazole without any effect on the substitution groups. If there are present other aromatic groups, they can not be easily affected at normal pressures. However, at higher temperatures and pressures, the 4,5,6,7 tetrahydrobenzotriazole derivatives can be formed after completion of the hydrogenation as can be determined by figuring the amount of adsorbed hydrogen. If the hydrogenation is then continued, and particularly where rhodium or platinum are used as catalyst, it is then possible also to hydrogenate the other aromatic groups.

To illustrate this, if l-phenylbenzotriazole is hydrogenated at C. and at a pressure of 1 kg./cm. only 1 phenyl 4,5,6,7 tetrahydrobenzotriazole is obtained. If the hydrogenation is then continued at C. and a hydrogen pressure of 50 kg./cm. there is obtained Z-cyclohexyl-4,5,6,7-tetrahydrobenzotriazole.

If pyridyl-substituted benzotriazoles are subjected to the hydrogenation of the invention, it is the yridine nucleus which is first saturated, followed by saturation of the benzene nucleus.

The catalysts used in the invention are the conventional palladium, platinum or rhodium catalysts which may be used as such or on different carrier materials. It is preferred to use the catalysts on carriers. Suitable carrier materials are, for instance, silicic acid, diatomaceous earths, aluminum oxide, pumice, asbestos, carbon, titanium dioxide, barium sulfate, vermiculite and silica gel. The platinum metals are usually employed in the carrier catalyst in amounts between 2 and 10%. The catalysts can be reused after thorough washing with, for instance, water, methanol or glacial acetic acid.

The process of the invention is carried out in a solvent or diluent in which the employed benzotriazole is at least partially soluble. Examples of such solvents are water, acetic acid, propionic acid, lower aliphatic alcohols, glycol ether, diethyl ether, tetrahydrofuran or mixtures of these compounds.

In a few cases it is possible to effect the hydrogenation of the benzotriazoles without the addition of a strong acid. Preferred, however, is the embodiment where a strong acid is used or, alternatively, where an acid addition salt is used as the starting product.

The invention can be practiced in a comparatively broad temperature range at normal pressure or superatmospheric pressure. The preferred temperature range at normal pressure is about 0 C. up to the boiling point of the solvent or diluent. Under these conditions it is preferred to use palladium as catalyst.

If a superatmospheric pressure is employed, the preferred catalysts are palladium and rhodium. If it is desired to apply the hydrogenation also to aromatic substituents, the process is effected preferably with rhodium, palladium or platinum catalysts. The hydrogenation can be carried out at a pressure between normal pressure and up to about 120 kg./cm. or more. The hydrogenation can also be effected at both highly elevated pressures and temperatures; this is possible in view of the starting product or desired end product.

The following Tables I-IV illustrate the results of the hydrogenation of benzotriazoles under varying conditions.

TABLE I The hydrogenation in this case was effected of 10 mmol 'benzotriazole in 30 ml. solvent at 1 atm. or at 60 atm. above atmospheric pressure employing 20 mmol benzotri- 6 in the form of a salt with a strong acid, the hydrogenation proceeds at a rapid speed and comes to completion (Table I, Test 7; Table II, Tests 49; and Table III, Test 2). This illustrates that the conditions normally used for difiiazole in 50 ml. solvent and using difierent catalysts on a 5 cult hydfogellfitlolls (Platlnllm and glaclal acetlc 801d) carbon carrier, the catalysts being present in an amount are not sufilcient here to successfully carry out the hydrof 5 genation (see Table II, Test 2). Only after addition of a Time of hydro- Pressure genation (hours) above Benzoatmos- Comtriazole, Catalyst Temp, pheric Half pletion Test number grams metal Solvent 0. (atm.) time time 1.2 60 1 5.2 1.2 It (0.1) 60 1 11.0 1.2 Rh (0.1) 60 1 Nohydrogenation. 1.2 Pd (0.1) 60 1 1.0 3.8 1.2 Pt (0.1) 60 1 4.0 1.2 Rh (0.1) 60 1 No hydrogenation. 1.2 Pd (0.1) 60 1 0.25 0.6 12 Pt (0.1) 60 1 1.0 2.2 l 1.2 Rh (0.1) 60 1 4.0 9.5 p 2.4 120 60 0.3 0.7 i 2.4 120 60 0.25 0.5 k A 2.4 120 60 0.25 0.5 A

1 Further very slow hydrogenation necessary. 1 N 01; complete after 30 hours. a 3 N o definite result.

TABLE II strong acid is it possible to effect hydrogenation with good yields (see Table II, Tests 5 and 8).

The activity of the platinum metals decreases upon hydrogenation at normal pressure and room temperature in the direction Pd Pt Rh, while it decreases at higher pressures and higher temperatures in the direction Rh Pd Pt.

Much easier is the hydrogenation of benzotriazoles which are substituted in the N-position, and particularly a carbon material. 3.) those substituted in the 2-N-position. In this case hydro- Time of hydro- Pressure genation (hours) above 5-carb0xyatrnos- Comtriazole, Catalyst Temp pheric Half pletion Test number grams metal Solvent; (atm.) time time 1. 6 P11 (0.1) 60 1 2. 5 6. 0 1.6 P1; (0.1) 60 1 Slow hydrogenation. 1. 6 Rh (1.0) 60 1 ow hydrogenation. 1.6 Pd (0.1) 60 1 1.1 2.5 1. 6 P1; (0.1) 60 1 5.0 1.6 Rh (0.1) 60 1 4.5 2.4 Pd (0.025) 120 60 0.3 0.7 2. 4 Pt (0.025) 120 60 0.8 1. 7 2. 4 Rh (0.025) d0 120 60 0. 3 0. 6

1 N o definite results.

A rapid hydrogenation was obtained when Tests 1-3 were repeated at a pressure of 60 atm. above atmospheric pressure and a temperature of 120 C.

TABLE III The hydrogenation in this case was effected with mmol (2.9 grams) 5,7-dimethyl-benzotriazole and a catalyst consisting of 1.5 g. Pd/BaSO in ml. solvent at 120 C. and a pressure of atm. above atmospheric pressure.

genation is sometimes possible in neutral solvents such as ethanol, dioxane or tetrahydrofuran. However, a substantial increase of the hydrogenation speed is obtained if strong acids are added (Table IV).

TABLE IV In this case 10 mmole of 2-ethyl-benzotriazole was hydrogenated in 30 ml. solvent using 1 gram of a 5% Pd/Ti0 catalyst and a temperature of 60 C. and a pressure of 1 atm. above atmospheric.

Hydrogenation Hydrogenation time (hours) time (hours) t Half Corn- Test Half Comnumber Solvent time pletion number Solvent time pletion 1 Glacial acetic acid 5 11 5 1 Ethanol 4,0 .0 2 Glacial acetic acid plus H2304 0. 8 1. 7 2 Glacial acetic acid 1, 5 3, 2 n 3 Glacial acetic acid plus 1.1 g. 150104..-. 0. 15 0. 35

The hydrogenation of benzotriazoles which are not N- substituted, such as benzotriazole itself (Table I), and of benzotriazoles which are substituted in the benzene nucleus of the benzotriazole, such as S-carboxybenzotriazole (Table III), S-methyland 5,7-dimethylbenzotriazole (Table III) is rather difficult. The hydrogenation in neutral solvent and at times even in glacial acetic acid proceeded only very slowly and remained very often incomplete. However, when the starting product is used It is accordingly of great significance for the invention to select the proper solvents. In addition to acetic acid and other lower carboxylic acids, it is possible to use water and other polar solvents such as lower aliphatic alcohols, glycol ether, diethylether or tetrahydrofuran, provided that the starting product is used in the form of its salt with an inorganic or organic acid or, alternatively, that in addition to the solvent an acid is added in an 7 amount of at least 1 equivalent for each basic group. If there is a deficiency in acid, either no hydrogenation takes place or the hydrogenation proceeds at a very slow speed and in some cases does not go to completion.

The Tables I-IV illustrate that the hydrogenation speed 8 ing the hydrogenation. The hydrogenation product is precipitated after cooling and then subjected to filtration.

Method D After removal of the catalyst by filtration the filtrate is depends on the type of catalyst and salt and, in addition, concentrated, the amount equivalent to the inorganic acid on the temperature d th pressure is added in alkali, and the solution is evaporated to dry- The preferred and most economical conditions for the ness. The residue is extracted with methanol or acetone, process of th invention are accordingly th following: the extract is concentrated, and if the hydrogenation prod- The hydrogenation preferably is carried out with Pd-, 10 uct does not crystallize it is precipitated with ether or an- Ptor Rh-carrier-catalysts in glacial acetic acid, diluted other suitable solvent. acetic acid, or water, upon addition of at least equimolar Method B amounts of StrPngFmdS Such as KH H604 This method is used in order to obtain the quaternary Thus t basic mtiogen gmults Whleh are present are ammonium salts. The method is employed with tetrahy Peutrahzed wlth'acld and Possibly acld e be Present 5 drobenzotriazoles of theabove formulae Ia and 1b in in an excess. The temperature for the reaction preferably which R is other than h d o 1 y rogen.

between g and the i i between 1 1 mole of the tetrahydro compound was dissolved in a and e Paitleularly eeonomleal i the hydro" small amount of methanol, and the solution was reacted genatlon water Wlth or panadlum catalysts with 1 mole of an alkyl, cycloalkyl or arylalkyl halide and upon addition of strong acids and at elevated temperatures 20 Permitted to react for an extended time at room tempera and pressures I ture or for a shorter period of time while being brought to The process of the mventlon resul.te m the formatlon an elevated temperature. After distilling off the solvent, of the salts of the tetrahydrobenzotrlazoles. In order to the quaternary ammonium Salt was Obtained in almost obtain the free acids, the steps are employed which are Pure form discussed below as Methods A to D. The Methods A to C Method F are useful for obtaining tetrahydrobenzotriazoles which do not for Salts with a base The tetrahydrohehzotrp This method is used for tetrahydrobenzotriazoles of the azoles which form salts with a base are preferably general formula Ia given above in which 1 is hydrogenprocessed according to the Method The tetrahydrobenzotriazole in this case is initially con- All parts stated below relate to weight-parts unless Vefted t0 the eofrespohdhig z-substihlted Compound otherwise stamp by reaction with an alkyl-, cycloalkylor aralkyl halide or -sulfate. SURVEY OF HYDROGENATION METHODS In frequent cases mixtures are obtained of 1- and 2- Method A isomers. The mixtures should then be separated and may 1 part of the starting product is hydrogenated with 0.01 be convene? to the corresponding quaternary ammonium to 1 part of a 5% Pd-, Ptor Rh carrier-catalyst in 10-20 aeeordmg to the abeve Method parts of solvent at normal pressure in a flask provided 1 some cases good yields are also obtemed m the iwith a magnetic stirrer. If a higher pressure is used, the owmg mannel} 1 mole of the compound ls process is carried out in an autoclave. The reaction teme aeeordmg to E Wlth 1 mole of an alkylperatures and pressures are summarized in Table V below. 5. ftryltllkyl hahde' Thereafter} .mole 9 After the calculated amount of hydrogen has been abg hy roxlde 18 added and the F t mlxture 1S sorbed, the catalyst is removed by filtration and the filas? i i After further. addmon 9 1 P of trate is subjected to concentration. The residue is then y 9 or arylalkyl hahde the mlxture 15 then dissolved in Water, made alkaline with sodium hydroxide, ."P for 1 9 upon reflux whereupon and the hydrogenation is obtained by filtration and if c pltated sodium salt s filtered off and the solvent is disnecessary, by extraction with a S 01 v ant The crude prod tilled off. There remains the quaternary ammomum salt. not is then subjected to recrystallization from a suitable EXAMPLE Solvent Method B The following is a complete example of one illustrative procedure.

The hydrogenation is carried out as in Method A. The 2.4 g. of benzotriazole were dissolved in 50 ml. water catalyst is removed by filtration, and the filtrate is suband 1 g. of concentrated sulfuric acid. The mass was then jected to concentration. The residue is dissolved in water subjected to hydrogenation in the presence of 0.5 g. of a and the solution is made alkaline. The hydrogenation palladium-barium sulfate catalyst at a temperature of product is then extracted with chloroform, trichloro- 120 C. and at. above atmospheric pressure. After conethylene, benzene or other water-immiscible solvents. The centration to about half its volume, the tetrahydrobenzoextract is dried on a drying agent, the solvent is distilled triazole was precipitated by adding ammonia. The preoff and the liquid product is distilled in a high vacuum or cipitate was taken up in glacial acetic acid ester and reconverted to the hydrochloride. crystallized from benzene. There were obtanied 2.2 g. of

M etho d C 60 tetrahydrobenzotriazole with a melting point of 75 C. I In reference to the above-described general Methods A The hydrogenation is carried out as in Method A. After to F, the following Table will furnish further examples removal of the catalyst by filtration and concentration of for making various hydrogenated tetrahydrobenzotri. the solvent, dilution is effected of the residue with water, azoles. whereupon the mass is reactedwith alkali in an amount In the following Table V, the pressure is given in atequivalent to the amount of acid which was present durmospheres above atmospheric pressure.

TABLE V Starting product (IIa, IIb) Conditions Final product (Ia, Ib)

Temp., (1 R1 Ra Ra Method Catalyst Solvent ii n 'i Compound No. p iei a ri t H H H A FYI/B9504.- H20+H2S04 120/60 4,5,6 ,7-tetrahydrobenzo- 1 36 l-ethyl H H B Pb/Tioz..-.- AcOH /1 1-ii ii1i l i?5',6,7-tetrahydro- 2 93 Liquid benzotriazole. Z-ethyl H H B Pic/carbon.-. AcOH 60/1 2-ethy1-4,5,6,7-tetrahydro- 3 92 Liquid benzotriazole.

TABLE VContinued Starting product (H21, 111)) Conditions Final product (Ia, Ib)

Temp., O./ press. Yield, M.P., R1 R R3 Method Catalyst Solvent atm. Compound No. percent C. l-hexadecyl H A Pd/carbon H O+HCl 60/60 1-hexadecyl-4,5,6,7-tretra- 4 89 52 hydrobenzotn'azole. l-carboxy- H H C Rh/carbon AcOH 120/60 1-carboxyethyl-4,5,6,7- 5 90 156 ethyl. tetrahydrobenzotriazole. l-methoxy- --..do AcOH 120/60 1-methoxyearbonyl- 96 Liquid carbonylethyl-4,5,6,7-tetrahydroethyl. benzotriazole. l-carboxy- Ptlcarbon HZO+H2SO4 60/1 1-carboxypropyl-(2)- 7 88 178 propyl(2). 4,5,6,7-tetrahydrobenzotriazole. l-phenyl H H A Pd/Ti0z AcOH+H2SO 80/1 1-pheuyl-4,5,6,7-tetra- 8 94 119 hydrobenzotriazole. Do H H A Ph/earbon AcOH-i-HClO; 120/60 1-cyclohexyl-4,5,6,7-tetra- 9 90 103 hydrobenzotriazole. l-benzyl H H A ...de AcOH 120/60 l-cyclohexylmethyl- 10 55 93 4,5,6,7-tetrahydrobenzotriazole. 1-, 4-acet- H H Pd/BaSO AcOH-I-HzSO; 120/60 1-, 4-acetaminobenzyl- 11 62 195 amino- 4,5,6,7-tetriahydrobenzyl. benzotriazole. H S-methyL. H A Pd/Ti02 AeOH-l-HCIO; 120/60 5methyl-4,5,6,7-tetra- 12 82 57 hydrobenzotriazole. H 5-carboxy- H D Pd/carbon-.- AcOH+HClO 120/60 5carboxy-4,5,6,7-tetra- 13 85 182 hydrobenzotriazole. H 4ruethyl- G-methyL. A Pt/BaSO HzO-l-HzSO; 120/60 4,6-dirnethyl-4,5,6,7-tetra- 14 83 82 hydrobenzotriazole. l-H 5-methy1 do. 13 Pt/Oz AcOH 120/60 5,6dimethy1-4,5,6,7-tetra- 15 93 Liquid hydrobenzotriazole. l-hexadecyl.-- 5-meth- H A Pd/TiO AcOH 60/1 l-hexadeeyl-S-methoxy- 16 72 46 oxycarcarbonyl-4,5,6,7-tetrabonyl. hydrobenzotriazole.

The tetrahydrobenzotriazoles were clearly identified from the infrared spectrum. The aromatic oscillations of the benzene nucleus, which are characteristic for unhydrogenated benzotriazoles (between 670 and 900 cm. depending on the type of substitution) are no longer noticeable in case of the hydrogenated compounds. The (HN) associated absorption betwen 2400 and 3500 CID-1, which is characteristic for the triazole nucleus, remains intact with the compounds which are unsubstituted in the N-position.

The tetrahydrobenzotriazoles made by the process of the invention can be used for different purposes, particularly as corrosion inhibitors, especially for copper and copper alloys. They can also be used for acid passivating agents for iron and steel, as inhibitors in metal restraining agents, as anti-aging agents in mineral oils, heat oils and rubber, and as intermediates for making pharmaceuticals and agricultural chemicals. The quaternary ammonium salts of the tetrahydrobenzotriazoles possess a strong surface-active effective and are suitable as wetting agents and softeners for textiles.

A few examples below will illustrate the use of 4,5,6,7- tetrahydrobenzotriazoles as metal-deactivators in lubricating oils. The tests were carried out according to AST M Standard D 130. A copper strip was immersed in a corrosive sulfur-containing mineral oil at an elevated temperature while an amount of 0.025% of the test compound was added. The mineral oil was a primary raffinate SAE 10 with sulfurized sperm oil and was adjusted to a total sulfur amount of 0.5%

The amount of discoloration of the copper strip was used as measure of the passivating action of the compound. The grading 1a to 40 was effected according to the color table as AST M D 130. The designations 1a to 3b indicate increasing discoloration. The designations 4a to 4c indicate strong increase of corrosion.

As the Table shows, the hydrogenated benzotriazoles have a better effect, particularly at increased temperatures, than the benzothiazole and the thiodiazole derivatives used heretofore for these purposes (see Tests 2 and 3).

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A 4,5,6,7-tetrahydrobenzotriazole of the group consisting of compounds having the following formulae:

R I N and Rr N R1 1'1. in which R is hydrogen or an alkyl radical containing up to 18 carbon atoms, and R is a carboxyl or lower alkoxycarbonyl radical, and acid addition and quaternary ammonium salts thereof.

2. A compound as defined in claim 1 which is 5-carboxy-4,5,6,7-tetrahydrobenzotriazole.

3. A compound as defined in claim 1 which is l-hexadecyl-S-methoxycarbonyl-4,5,6,7-tetrahydrobenzotriazole.

4. The compound of claim 1 wherein alkyl in R has from 1 to 4 carbon atoms.

5. A process for the production of a 4,5,6,7-tetrahydrobenzotriazole as defined in claim 1 which comprises passing a stream of hydrogen into a solution of a benzotriazole of the group consisting of compounds having the following formulae:

\N and R \NR1 s 1'1. in which R is hydrogen or an alkyl radical containing up to 18 carbon atoms and R is a carboxylic or lower alkoxycarbonyl radical in a solvent therefor containing a strong acid in an amount that is suflicient to neutralize the basic nitrogen atoms of the benzotriazole and a catalyst of the group consisting of platinum, palladium, and rhodium hydrogenation catalysts until the benzotriazole has absorbed an amount of hydrogen that is stoichiometrically equivalent to that required to form the corresponding tetrahydrobenzotriazole and subsequently recovering the resulting tetrahydrobenzotriazole.

6. A process as defined in claim 5 in which the strong acid is an acid of the group consisting of hydrochloric acid, sulfuric acid, and perchloric acid.

7. A process as defined in claim 5 in which the solvent is water, acetic acid, propionic acid, a lower aliphatic alcohol, a glycol ether, diethyl ether, tetrahydrofuran, or a mixture of these solvents.

8. The process of claim 5, wherein the triazole salt obtained is converted to the free base by reaction with alkali.

9. The process of claim 8, wherein the free base obtained is reacted with acid to obtain the acid addition salt.

10. The process of claim 8, wherein the free base is dissolved in methanol and the solution is reacted with an alkyl-, cycloalkylor arylalkyl halide to form the quaternary ammonium salt.

11. The process of claim 5, wherein the palladium-, rhodiumor platinum catalyst is employed on a carrier ma.- terial.

12. The process of claim 11 wherein the carrier material References Cited UNITED STATES PATENTS 3,197,475 7/1965 Carboni 260308 B FOREIGN PATENTS 1,577,580 6/1969 France 260308 B OTHER REFERENCES Croce et a1.: Gazz. Chim. Ital., vol. 97, pp. 589596 (1967).

ALTON D. ROLLINS, Primary Examiner US. Cl. X.R.

252-50, 51.5 R, 390, 392; 260-21l.5 R, 247.2 R, 247.2 A, 247.5 E, 268 BC, 293.59, 308 D 

1. A 4,5,6,7-TETRAHYDROBENZOTRIAZOLE OF THE GROUP CONSISTING OF COMPOUNDS HAVING THE FOLLOWING FORMULAE: 